An apparatus for supplying minute liquid droplets in a designated amount at a designated location is known. For example, an inkjet printer dispenses ink droplets at specified positions on a recording medium, such as paper, to form images or characters. Inkjet printers include an inkjet head which ejects the ink droplets according to an image signal. In another example, a liquid dispensing apparatus supplies a reagent for pharmaceutical and biological research and development or medical diagnosis and examination in a predetermined amount into a predetermined container. Additionally, a three-dimensional (3D) printer somewhat similarly supplies a liquid resin in a predetermined amount at a predetermined location at predetermined time so as to perform 3D printing. The inkjet printer, the dispensing apparatus, and the 3D printer can each be equipped with a liquid jetting device which ejects minute liquid droplets according to control data. An inkjet head is an example of a liquid jetting device.
A known inkjet head includes a piezoelectric body having a groove serving as an ink flow path, an electrode formed in the groove, and a nozzle plate having nozzles from which ink can be ejected. A plurality of such grooves is formed and an electrode is formed inside each groove. A piezoelectric body between two adjacent grooves operates as a piezoelectric element supplying pressure on ink in the ink flow path. Adjacent piezoelectric elements are driven at a same time so as to expand or contract the volume of the ink flow path. By expansion and contraction of the ink flow path, ink in the ink flow path can be ejected from the nozzle. The piezoelectric elements are driven by an integrated circuit. However, repeated ink ejections cause the integrated circuit to generate heat.
If the temperature of the integrated circuit rises too high, the integrated circuit may be damaged.